Question

Ralph bought 3 boxes with 20 pencils each and 4 boxes with 10 pens each. To find the total number of pencils and pens, Ralph evaluated 3×20+4x10=720. is his answer reasonable? Explain.​

Answer 1

No, it's actually 100

Explanation:

If you put brackets in the right places you'll see (3*20)+(4*10)=60+40=100