SASMO 2018 Secondary 1 (Grade 7) Contest Question 10

Machine A can produce 450 cheese blocks in m hours. If machine A and
machine B work together at their respective rates, their combined production in
n hours is 450 cheese blocks altogether. If machine B works alone, how long, in
hours, would it take to produce 450 cheese blocks?
m=n
A Fou
mxn
ey
n
Oa
nom
De xn
mxn
aa