Brenda, the key is to recognize that you need to convert the percentages into amounts.
You start with 2 quarts of liquid that is 25% antifreeze, or you have 2 x .25 = .5 quarts of antifreeze to start with.
You are going to add another amount of liquid that is 100% antifreeze or you are going to add
L quarts of liquid and 1 x L quarts of antifreeze
When you are finished you are going to have L+2 quarts of liquid and L+.5 quarts of antifreeze, and
when we are finished we want the antifreeze content to be 60% or we want
L+2 quarts of liquid that is 60% antifreeze or L+.5 quarts of antifreeze, so
.6L + 1.2 = L+.5
-.6L - .5 = -.6L -.5
L= 1.75 quarts of Antifreeze.
1.75+.5 quarts of antifreeze=2.25
2+1.75 quarts of fluid = 3.75
I hope this helps. John