CPhill

Let N be the number of weeks she has received the $20.

So we have

20N + 100 = 320     subtract 100 from each side

20N = 220              divide both sides by 20

N = 11      ...so, she has been saving for 11 weeks

a)

80/1250 = x/4000   cross-multiply

4000(80) = 1250x     simplify

320000 = 1250x       divide both sides by 1250

320000/1250 = x = 256  

b) 

$1.19/32 =x/256           again, cross-multiply

304.64 = 32x                divide by 32 on both sides

$9.52 = x

Note...3 + 1/4 = 3.25      so we have

5800/1hr = x /3.25hrs     cross multiply

3.25 * 5800  = 1x

18850  = x         and that's how many they can print in 3.25 hrs

Since he pays out $600 each month and he wants to make a proit of $500, he must collect $500 more than his expenses....so.....600 + 500 = 1100  ....so he must collect $1100 in rent from the 4 apartmenrs.

And the amount he must collect from each is just  $1100/4 = $275

7/7 = 1  ...... so.......

7 + 1 + 1 = 9

5(x-3)+12 = -2(x+7)      distribute the 5 and -2 over the terms in the parentheses

5x - 15 +12 = -2x - 14    simplify

5x - 3 = -2x -14              add 3 to both sides and add 2x to both sides

7x = -11                          divide both sides by 7

x = -11/7

Note that y appears to change by 1 when x changes by 4.......so the slope of our function is 1/4

And using one of the points (12, 2.5)   we have  ...in point-slope form ....

y - 2.5 = (1/4)(x - 12)      add 2.5 to both sides

y = (1/4)(x - 12) + 2.5     distribute the 1/4 across the terms in the parentheses

y = (1/4)x - 3 + 2.5         simplify

y = (1/4)x - 1/2             so when x = 8, y should = 1.5...let's see if that's true

y = (1/4)(8) - 1/2

y = 2 - 1/2 

y = 3/2 = 1.5

So....our equation is correct

Thanks, Anonymous...here's another way

Let x = 0   so we have

y = 5 -3(0)

y = 5 - 0

y = 5     .........so the point  (0, 5) is on the graph

Next, let y = 0   so we have

0 = 5 - 3x        add 3x to both sides

3x = 5         divide by 3 on both sides

x = 5/3       so the point (5/3, 0) is also on the graph

Plot both points and draw a line between them....there's your graph!!!!

(11.3 - p)/2.8 = 1.5      multiply both sides by 2.8

11.3 - p = 4.2             add p to both sides and subtract 4.2 from both sides

7.1 = p

-8 = -8/1   so we have

-8/1 ÷ 1/2       invert the second fraction and change to multiplication

-8/1 x 2/1   =  -16/1  = -16