In your head, you should be able to add 15 and 5. The answer is 20. You should also be able to work out 20 + 9. The answer is 29. The trick to doing well at these types of questions is finding the quickest and easiest method of working them out. It will come with practice :)
Answer:
15 boys
Step-by-step explanation:
50 x .30 = 15
Step-by-step explanation:
2x + 5 (y-1)
16+20
=36
hope it helps you