Answer:
5 * 15 = 75
3 * 15 = 45
45 + 75 = 120
Explanation:
When you have a equation like that, you need to multiply. It is a faster way to solve the problem.
You had 15 five times.
15+15+15+15+15= 75 It equals the same thing because it is the same as 5 * 15
Same for the three fifteens.
15+15+15= 45.
The sum of the whole equation is 120 because you add 75 and 45.
Hope this helps, have a good day/night. Stay safe and healthy!