What is 1 and 3/4-7/10

We first have to change the mixed number into a fraction and we do this by multiplying the denominator to the whole number and adding the product to the numerator.
It looks something like this:

4×1=4         (Multiply the denominator and the whole number)
4+3=7         (Add the product and the numerator)
 
Keep the same denominator 
Now that we have the improper fraction, we can subtract.

Now in order to subtract we have to have a common denominator, so lets make both of the denominators 20.
 ×  = 
 ×  = 

21÷20=1.05 or 
If you have any questions, feel free to ask. Hope that helped :)