help me,besok sy mau usbn.sy gk ngerti ini tolong ya

u3= a+2b=36
u5+u7= a+6b+a+4b=144
a+2b=36
2a+10b= 144

2a+4b=72
2a+10b=144
-6b=-72
b=12


a+2b=36
a+2(12)=36
a=12

S10= 10/2 (2(12) + 9(12)
=5(24 + 108)
=5 (132)
=660