Answer:
4
Explanation:
Let x equal the unknown number.
Sum means we're dealing with addition.
Twice and half means we're dealing with multiplication (and/or divison).
Written out, the sum of 2 times some number (x) PLUS half that same number (x) is equal to 10.
So, lets put 10 on one side:
10 = some equation
Put the variables on the other side:
some number = 2x + .5x
Set them equal to each other and solve algebraically:
10 = 2x + .5x
Combine like terms: 2x and .5x
10 = 2.5x
Divide both sides by 2.5x
4 = x
Final answer:
x = 4
Hope this helps!