Let’s start by first finding the cost of 1 candy bar. We have to divide 1.80 by 6 to find the cost of 1 water bottle and 4.20 divided by 6 to find the cost of 1 candy bar. 1 water bottle= 30 cents (0.3) and 1 candy bar= 70 cents (0.7). Now, to find how much he spent on 18 water bottles we must multiply 18 by 0.3 which = $60 and multiply 28 by 0.7 = $19.60 (19.6). Now add 19.60 + 60 = 79.60 (79.6)
So, Frank spent $79.60 on food total. Sorry if I got it wrong, but hope this helps!
