3s+b=105 subtract 3s from both sides
b=105-3s...then we are told that:
2s+2b=98, using b found above we have:
2s+2(105-3s)=98 perform indicated multiplication on left side
2s+210-6s=98 combine like term on left side
-4s+210=98 subtract 210 from both sides
-4s=-112 divide both sides by 4
s=28, since b=105-3s
b=105-3(28)
b=105-84
b=21
So a scarf costs $28 and a belt costs $21 respectively.
The wording is a little wonky, but the cost of a scarf and a belt together is:
28+21=$49