1278, помогите пожалуйста

4x+9y-9=0
5x-6y-17=0
X=-9/4y+9/4
5x-6y-17=0
5(-9/4y+9/4)-6y-17=0
y=-1/3
x=-/4*(-1/3)+9/4
x=3
y=-1/3
1,5x-1,2y+18=0
0,7x-1,8y+14,6=0
×=2y/25-6/5
0.7x-1.8y+14.6=0
0.7(2y/25-6/5)-1.8y+14.6=0
y=860/109
x=2*860/109 /25-6/5
x=-62/109
X=-62/100
y=860/109