The first thing you should do is calculate the money earned by selling the chocolate donuts. We have then:
chocolate = (2) * (978) = 1956 $.
To know the amount of vanilla donuts sold you must first calculate the gain in vanilla donuts by subtracting the total gain with the gain of the chocolate
donuts:
vanilla = (4378) - (1956) = 2422 $
The amount of vanilla donuts at $ 2 per donut is:
# vanilla donuts = (2422) / (2) = 1211
answer
they sold 1211 vanilla donut
