"the difference of a number x and 4": x - 4
"is": =
"3": 3
Combine the terms so that it looks like the sentence numerically:
"the difference of a number x and 4 is 3": x - 3 = 4
x - 3 = 4 is your answer.
To solve for x:
Note the equal sign, what you do to one side, you do to the other. Isolate the variable, x. Add 3 to both sides.
x - 3 = 4
x -3 (-3) = 4 (-3)
x = 4 - 3
x = 1
1 is your answer for x.
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Remember that the radicand (the area under the root sign) must be positive or zero for a radical with an even index (like the square root or fourth root, for example). This is because two numbers squared or to the fourth power, etc. cannot be negative, so there are no real solutions when the radicand is negative. We must restrict the domain of the square-root function.
If the domain has already been restricted to

, we can work backwards to add 11 to both sides. We see that

must be under the radicand, so the answer is
A.
3 casseroles feeds 15 people
The ratio is 3:15
If you divide each of those by 3, youll find that 1 casserole feeds 5 people
1 : 5 is the ratio.
Divide 30 by 5 = 6
6 casseroles feeds 30 people.
6 : 30
35 divided by 5 = 7
7 casseroles feed 35 people
7 : 35