72°35'÷2+18°33'×4
=72°34'60''÷2+72°132‘
=36°17’30‘’+74°12‘
=110°29’30‘’
Y-(Y-1)/2=2-(Y+2)/5
两边乘以10得
10y-5(y-1)=20-2(y+2)
10y-5y+5=20-2y-4
7y=11
y=11/7