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how do you solve c=3d-27 ; 4d+10c=120

• 8th grade -

(1) c = 3d - 27
(2) 4d + 10c = 120
there are several ways to solve this problem (system of linear equations),, but in this case, we substitution method since in equation (1), variable c is expressed in terms of the other variable d,, we then substitute c from equation (1) to equation (2):
4d + 10(3d-27) = 120
4d + 30d - 270 = 120
34d = 390
d = 195/17

*substituting this value of d to either equations (in this case, to (1)):
c = 3d - 27
c = 3(195/17) - 27
c = 585/17 - 27
c = (585 - 459)/17
c = 126/17

so there,, :)

• 8th grade Math -

How do you solve this problem? V = Bh

Solve each formula for the variable shown in RED. In this problem the variable in RED is the letter B.

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