8th grade
posted by wendy .
how do you solve c=3d27 ; 4d+10c=120

(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(3d27) = 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,, :) 
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.