Choose the equivalent expression for 13(15m+3b−21).

5m+3b−7

5m+b−7

45m+9b−63

5m+3b−21

5m + b -7

Step-by-step explanation:

15m + 3b -21 can be simplified to 5m + b -7 by dividing 3

second option

step-by-step explanation:

the measures of a triangle equal 180. use that to find x.

2x+3x+4x=180

9x=180

9x/9=180/9

x=20

now you know x, you know angle a is 40°, angle b is 60°, angle c is 80°.

because angle a is 40°, the first option doesn't work.

because angle b is 60°, the second option does work.

when you add angle a and b, you get 100°. complementary means it equals 90°, so the third option doesn't work.

when you add angle a and c, you get 120°, which is not 100.

answer: answer is b.

[m < b = 120º]

step-by-step explanation: