tolong bagaimana cara nyri nya

38. rata"=15.8+16.4+17.6+18.9+19.8+20.5/8+4+6+9+8+5
rata"=120+64+102+162+152+100/40
rata"=700/5=17,5(A)

39. rata"(gab)=rata"1.n1+rata"2+n2/n1+n2
150,8=150.n1+152.12/n1+12
150,8=150.n1+1824/n1+12
150,8(n1+12)=150.n1+1824
150,8n1+1809,6=150.n1+1824
150,8n1-150n1=1824-1809,6
0,8n1=14,4
n1(perempuan)=18(D)