Question

Y is partly constant and partly varies as x. When x=2,y=16 and when x=7,y=31,find y in terms of x.

Answer 1

Y is partly constant and partly varies as x.
So, y = mx+b
Using the points,
2m+b = 16
7m+b = 31
subtract, and you get
5m = 15
m = 3
so, b = 10

y = 3x+10