Answer:
$3
Step-by-step explanation:
7 rand = 1 dollar
Divide both sides by 7 rand.
1 = (1 dollar)/(7 rand)
Notice that the fraction (1 dollar)/(7 rand) equals 1, so multiplying by it will not change the amount, just the units.
21 rand * (1 dollar)/(7 rand) =
= 21/7 dollar
= 3 dollar = $3
