For every $5 I earn from my job, I save $2. For every $4 I save from my job, I am given an additional $1 from my parents to add to my saving. How much must I earn in order to have $40 in savings?
x = # $5 unit you earn
2x = amount you save per unit
2x/4 = amount from parents
2x + 2x/4 = 40
10x/4 = 40
10x=160
x = 16 $5 units = $80 (oops....corrected 16 x5 = 80 not 75 as I originally posted)
We have this equation
( [ E / 5 ] *2 ) + [ ( [ E / 5 ] ) * 2 ] / 4 = 40 where E is the amount you earn
Simplify
(2/5)E + (1/10)E = 40
(4/10)E + (1/10)E = 40
(5/10)E = 40
(1/2)E = 40 multiply by 2
E = 80
Check
For $80 you will save (80 / 5) * 2 = 16 * 2 = $32
And your parents give you 32/4 = $8 more