I will solve your system by substitution (you can also solve this system by elimination).
#4x−y=10#
#3x+5y=19#
Step: Solve #4x−y=10# for #y#:
#4x−y+−4x=10+−4x" "# (add #-4x# to both sides)
#−y=−4x+10#
Divide by #-1#
#y=4x−10#
Step: Substitute #4x−10# for #y# in #3x+5y=19#:
#3x+5y=19#
#3x+5 (4x−10)=19#
#23x−50=19 " "#(simplify both sides of the equation)
#23x−50+50=19+50 " "#(add #50# to both sides)
#23x=69#
Divide both sides by #23#
#x=3#
Step: Substitute #3# for #x# in #y=4x−10#:
#y=4x−10#
#y=(4)(3)−10#
#y=2" "# (simplify both sides of the equation)