tolong bantu no. 3 ya, besok dikumpylkan

pf(panjang foto) = 40 cm
lf(lebar foto) =60 cm
pb(panjang bingkai) =40 + 2,5 + 2,5 = 45 cm
lb(lebar bingkai) =60 + 2,5 + x=62,5 + x

pf/pb=lf/lb
:40/45 = 60/(62,5+x)
:2/45 = 3/(62,5+x)
:135=2(62,5+x)
:135=125+2x
:10=2x
x=5 cm