If y varies directly with x, and if x = 7.5 when y = 10, how do you find x when y = 4?

Question

4447 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2018-05-27T23:24:41

#x = 3#

#y# varies directly with #x#

#y ∝ x#

#y = kx#

Where #k# is proportionality constant

If #x = 7.5# then #y = 10#

#k = y/x = 10/7.5 = 4/3#

When #y = 4#

#x = y/k = 4/(4/3) = cancel(4) × 3/cancel(4) = 3#