Hi there! I'm here to help. :)
Okay, so here you are solving for x. To solve for x, you must get it alone on one side of the equal sign. As we can see, it is not alone, and it is with 1 1/4 on the left side of the equal sign.
To get it alone, we need to subtract 1 1/4 from both sides. However, to subtract fractions, we need to make sure they have the same denominator. Looking at the fractions, we can see that they have two different denominators.
Begin by converting both fractions into improper fractions:
1 1/4 = 5/4
3 1/2 = 7/2
So now our equation looks like this: x + 5/4 = 7/2
Now we need to make it to where we our fractions have the same denominator.
Our current denominators are 4 and 2. The LCM (lowest common multiple) of 4 and 2 is 4, so you leave 5/4 as it is (because it's denominator is already 4) and you change 7/2.
Multiply 2 * 2 to make the denominator 4 in 7/2, but whatever you do to the denominator, you MUST do to the numerator. So multiply 7 * 2 = 14. Now your fraction looks like this: 14/4
Now we have:
1 1/4 = 5/4
3 1/2 = 14/4
Our denominators are the same now! Now here comes the easy part: We subtract! Do 3 1/2 - 1 1/4, or, 14/4 - 5/4. To subtract fractions, simply subtract the numerators and leave the denominators as is. 14 - 5 = 9, so 14/4 - 5/4 = 9/4.
Now our equation looks like this:
x = 9/4
LASTLY: All of your options are mixed numbers, so convert this improper fraction back into a mixed number. 9/4 = 2 1/4.
So, x = 2 1/4. :)