Please help, I don't understand this​

After substitution in the first equation :

7x + x +21 = -19

= 8x + 21 = -19

by subtracting 21 :

8x = -19 - 21

8x = -40

by dividing over 8 :

x = -5

after substitution in the second equation :

2y = -5 + 21

2y = 16

by dividing over 2 :

y = 8

pls give me brainliest

828. all there is to it!

here, if you ever need with rounding (or other forms of arithmetic/math) again, use this:

thats the rounding one, but if you just click the top left, it shows you all the calculators you may need!

b

step-by-step explanation:

a difference is the result of subtraction. while each of these expressions has subtraction in it, a difference will be the result when subtraction is the last operation applied in the order of operations for the expression. this means subtraction must be outside of the parenthesis. only b has this.