Answer:
number of commercials: 6
Number of movies: 4
Explanation:
Let x = the number of commercials
Let y = the number of movies
30x + 110 y = 620
x + y = 10 This can be written y = 10 - x (substitute 10 - x for y)
30x + 110y = 620
30x + 110(10 - x) = 620 Distribute the 110
30x + 1100 - 110x = 620 Combine like terms
-80x + 1100 = 620 Subtract 1100 from both sides
-80x = -480 Divide both sides by -80
x = 6
There are 6 commercials.
Substitute 6 for x
x + y = 10
6 + y = 10 Subtract 6 from both sides
y = 4
There are 4 movies.
Check:
x + y = 10
6 + 4 = 10
10 = 10 checks
30x + 110y = 620
30(6) + 110(4) = 620
180 + 440 = 620
620 = 620 checks