find the number of running and passing plays using substitution method 110 plays 3 yards per run 7 yards per pass total yards 378

Let x be the number of running plays

Y be the number of passing plays

Since the total plays is 110

X + y = 110

And total yard is 378

3x + 7y = 378

Using the first equation

X = 110 - y and substitute to the 2nd equation

3 (110 - y) + 7y = 378

And solve for y

Y = 12

Substitute to eqution 1

X = 110 - 12 = 98