
x is party constant and partly varies as y. When y = 2, x = 30, and when y = 6, x = 50

Find the relationship between x and y

Find x when y = 3
Solution:
Solution:
X is partly constant and partly varies as y"
—> x = ky + p
Where k and p are constant.
when y=2,x=30 —> 30 = 2k + p
when y=6,x=50 —> 50 = 6k + p
subtract: 20 = 4k
k = 5
sub back in the first: 30 = 10+p
p = 20
x = 5y + 20
notice this is just a variation of y = mx + b.
x = c + k y
Solving the two equation below simultaneously, we have:
30 = c + 2k
50 = c + 6k
subtract
20 = 4k
k = 5
so 30 = c + 10
c = 20
x = 20 + 5 y or y = x/5 4
and if y = 3 then
x = 20 + 5×3 = 20+15 = 35
x = 35 Ans.