"A trucking firm has 8 trucks, some carry a load of 10 tonnes and others carry a load of 5 tonnes. When all 8 trucks are carrying a full load, the total load is 70 tonnes." Develop and solve simultaneous equations to determine the number of trucks of each size that the trucking firm has.

Answer 1

total trucks: x+y = 8
total loads: 10x + 5y = 70

I expect you can solve that with little difficulty.