If b varies jointly with a and c and b = 112 when a = 12 and c = 7, find a when b = 72 and c = 2

Given:

b jointly varies with a and c. This can be written as,

where k is a constant.

We need to determine the value of a when b = 72 and c = 2

Value of k:

Also, given that the value b = 112 when a = 12 and c = 7.

Hence, substituting these values in the expression , we get;

Thus, the value of k is

Value of a:

The value of a can be determined by substituting b = 72, c = 2 and in the expression , we have;

Therefore, the value of a is 9.

hello :

70y^8 + 30y^6 = 2 ( 35 y^8 + 15y^6)

the lenght is : 35 y^8

the width is : 15y^6