P varies jointly as M and N, if P = 72 when M = 9 and N = 8, what is the value of M when P = 12 and n = 8?
2 answers
M = 4
p = km + n
for p = 72 and m = 9 and n = 8 , we have
72 = 9k + 8
9k = 64
k = 64/9
p = (64/9)m + n
when p = 12, and n = 8
12 = (64/9)m + 8
4 = (64/9)m
m = 36/64 = 9/16
for p = 72 and m = 9 and n = 8 , we have
72 = 9k + 8
9k = 64
k = 64/9
p = (64/9)m + n
when p = 12, and n = 8
12 = (64/9)m + 8
4 = (64/9)m
m = 36/64 = 9/16