When is 9+10 really equal to 21

9 + 10 = 21

Step-by-step explanation:

9 + 10 = 21

Factor out 9 and 10

9 = 3 · 3   10 = 2 · 5

Next multiply 3 by 2

3 × 2 = 6

Then multiply 3 by 5

3 · 5 = 15

Finally add the products

15 + 6 = 21

x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x

step-by-step explanation:

last month maria hiked the 5-mile mountain trail a number of times and she hiked the 10-mile canal trail several times. let x represent the number of times she hiked the 5-mile trail, and let y represent the number of times she hiked the 10-mile trail. if she hiked a total of 90 miles, which equation can be used to find the number of times maria hiked each trail? x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x