Harold brought three pounds of red apples and 4.2 pounds of green apples from the grocery store we're both kinds of apples are $1.75 a pound how much did Harold spend on apples

So you multiply because you want to find out the cost of the total amount of apples per pound bought. You multiply 3 and 1.75 and you should get $5.25 for red apples. You multiply 4.2 pounds and 1.75 and you should get $7.35 for green apples.