The price of a repeated set, film 2 of 2

A caterer bought spring rolls, samosas and satay sticks. 2 fifths were spring rolls and a quarter were samosas. A spring roll cost as much as 2 samosas or 3 satay sticks. The caterer spent one hundred and seventy dollars more on spring rolls than on satay sticks. How much did the caterer spend altogether? Try it first. Pause if you like. First, how many of each. 5 and 4 both go into 20. 20 is the lowest common multiple of 5 and 4, so write every share out of 20. 8 twentieths are spring rolls, 5 are samosas. That leaves 7 for the satay sticks. So the quantities are 8 to 5 to 7. Now how much each one costs. A spring roll is worth 2 samosas. Write it down. And a spring roll is worth 3 satay sticks. Both lines are about the spring roll. It's a 2 in one and a 3 in the other. Make the spring roll the same number in both. 2 and 3 both go into 6. Multiply the first line by 3, and 2 to 1 becomes 6 to 3. Multiply the second by 2, and 3 to 1 becomes 6 to 2. Now the spring roll is 6 in both, so the three go together. 6 to 3 to 2. Now multiply straight down. 8 spring rolls, each worth 6. 5 samosas, each worth 3. 7 satay sticks, each worth 2. That bottom row is money. 48 to 15 to 14. There are 48 minus 14 more units on the spring rolls than on the satay sticks. That's 34 units. And the question says those 34 units are one hundred and seventy dollars. So 1 unit is one hundred and seventy divided by 34. That's 5 dollars. Add the bottom row. 48 and 15 and 14 is 77 units. 77 times 5 is three hundred and eighty five. That's what the caterer spent. One ratio counts them. One ratio prices them. Multiply the two straight down, and the bottom row is money.