in the solution to using substitution method to solve this simultaneous equation

y-1/4x=3
and
3y+x=23

from

y-1/4x=3 we get y = 1/4 x + 3
sub that into the other equation
3(1/4 x + 3) + x = 23
(3/4)x + 9 + x = 23
(7/4)x = 14
x = 14(4/7) = 8
then y = (1/4)(8) + 3 = 5