Answer:
Car B = 43 miles per gallon
Car A = 43+4=47 miles per gallons
Step-by-step explanation:
Let the mileage of Car B be x miles per gallon
Hence the mileage of Car A will be x+4 miles per gallon
Distance traveled by each car in 1 gallon
Car A = x+4
Car B = x
Total Distance covered by both car in 1 gallon = x+(x+4) which is given as 90 miles
Hence x+(x+4)=90
2x+4=90
2x=86
dividing both sides by 2 we get
x=43
Mileage of Car B = 43 miles per gallon
Mileage of Car A = 43+4=47 miles per gallons