Can I use "suppose" and "if" together?

[jokaec1]

For example, "Suppose, if I go on a trip to Mexico in the off-season, will I get a discount on both airfare and hotels?"

 

[emsr2d2]

Before answering your question, please correct certain errors in your post. There should not be a capital letter on "if" because it's after a comma. You need "a" before "discount" and a question mark at the end.

 

[jokaec1]

Before answering your question, please correct certain errors in your post. There should not be a capital letter on "if" because it's after a comma. You need "a" before "discount" and a question mark at the end.

Thank you, I corrected my mistakes. So, can you help me answer my question?

 

[emsr2d2]

They don't go well together. You can say "Suppose I go on a trip to Mexico in the off-season. Will I ...?" You could also say "If I go on a trip to Mexico in the off-season, ...?"

 

[Raymott]

For example, "Suppose, if I go on a trip to Mexico in the off-season, will I get a discount on both airfare and hotels?"

This should be two sentences. The first ('Suppose ...') is an instruction. It's imperative. The second ("will I ...") is a question whose answer is based on the condition. "Suppose, if" is wrong, and so is "Suppose if" (in this context).
It's similar to a simple maths problem. "Let X be 3 and y be 4. What is x + y?"
You can't write "Suppose x is 3 and y is 4, will x+y be 7?"