I will try to solve your system of equations.
3x+3y=4;2x+7y=8
Step: Solve3x+3y=4for x:
3x+3y+−3y=4+−3y(Add -3y to both sides)
3x=−3y+4
3x3=−3y+43(Divide both sides by 3)
x=−y+43
Step: Substitute−y+43forxin2x+7y=8:
2x+7y=8
2(−y+43)+7y=8
5y+83=8(Simplify both sides of the equation)
5y+83+−83=8+−83(Add (-8)/3 to both sides)
5y=163
5y5=1635(Divide both sides by 5)
y=1615
Step: Substitute1615foryinx=−y+43:
x=−y+43
x=−1615+43
x=415(Simplify both sides of the equation)