How to use order of operation in 20 divide by 4 multiply 5 = 1

Cora bought a package of erasers. there are 4 pink erasers and 12 blue erasers. what is the ratio of pink erasers to blue erasers?

Can someone check if i did this correct. it’s number 4 if you’re wondering.

Technicians have installed a center pivot, circular irrigator for a farm that covers 25 acres. a.) how long is the irrigation boom (in feet) from the center pivot to its farthest extent? b.) if the irrigation boom makes 4 full revolutions in a day, how many miles does the end of the boom travel in 5 days?