X is partly constant and partly varies as y.when y=2,x=12 and when y=4,x=18.find x when y=1

Answer 1

x is partly constant and partly varies as y ----> x = my+b
using the given points, we have
2m+b = 12
4m+b = 18
That yields x = 3y+6
s0 x(1) = 3+6 = 9