If 3s+5t = 10, and 2s-2=7, what is the value of 0.5s + 3t?
If 2s - 2 = 7 add 2 to both sides
2s = 9 divide both sides by 2
s = 9/2 and substituting this into 3s + 5t = 10 to find t, we have
3(9/2) +5t = 10
27/2 + 5t = 10 subtract 27/2 from both sides
5t = 10 - 27/2
5t = 20/2 - 27/2
5t =-7/2 divide both sides by 5
t = -7/10
And substituting these values into .5s + 3t, we have
.5(9/2) + 3(-7/10) =
(1/2)(9/2) - 21/10 =
9/4 - 21/10 =
[90 - 84] / 40 =
6/40 =
3/20
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