2 answers
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90 min = 1.5 hr
(x+20) *1.5 + x*1.5 = 18
x+20 + x = 12
ah, I think maybe you mean (x+ 2) km/h
90 min = 1.5 hr
(x+2) *1.5 + x*1.5 = 18
x+2 + x = 12
2x = 10
x = 5 km/h
x+2 = 7 km/h
5*1.5 = 7.5 km
7*1.5 = 10.5 km
yes the sum is 18