Question

p + q = 1000 p is 150 greater than q calculate numbers p & q

Answer 1

Because p is 150 greater than q we can substitute p like p = 150 + q. 
When we plug this in it looks like this
(150 + q) + q = 1000
subtract 150 from the left side
q + q = 850
2q = 850
divide 2 to get q alone
q = 425