The cost of a T-shirt was two times as much as the cost of a pair of socks. Joe bought 3 pairs of socks and 1 T-shirt for $100. Find the total cost of 1 T-shirt and 2 pairs of socks.
+592 lets call the cost of a pair of socks $s$, and the cost of the T-shirt is $t$. we have:
$2s=t$
$3s+t=100$
we can substitute $t$ for $2s$:
$3s+2s=100=5s$
$s=\dfrac{100}5=20$
$2\cdot20=t=40$
so:
$t+2s=40+40=\boxed{\$80}$
