An engine with an input temperature of 755K and an exhaust temperature of 453K has the same efficiency as an engine that is 40% efficient. Is this true or false? I am having trouble

Efficiency is usually defined as a benefit divided by a cost. Or in terms of temperature:

e=1 - T cold / T hot

Here, you are given both temperatures, so you just need to plug them in, and then compare to 40%. You will get a decimal for 'e', so you'll have to multiply by 100 to get a percentage.