Answer:
130
Step-by-step explanation:
31+19=50
Angle in a triangle add up to 180
180-50=130
3/4 * 5/7 = 15/28 or 0.5357
(8x-10)°+(6x)°+(10x+10)°=360°
8x-10+6x+10x+10=360
8x+6x+10x-10+10=360
24x-10+10=360
24x=360
24x/24=360/24
x=15
Scalene because all three sides are different.
$80-$2= $78 is the number less than $80, since the pens cost $2
78/2= 39 pens is the greatest number of pens sold
hope this helps
Step-by-step explanation:
Well in general, we can represent subtraction as: 
"z" represents the difference, and it really just represents x with y taken away. So if we were to "give back" this y value, we should get "x".
This means that: 
So one way to check, is adding the value that's being subtracted (y value) and the difference (z value), this should get you the value that is being subtracted from (x value). If you don't get the original value that's being subtracted from (x-value) then you know the answer you got is wrong.