An equation is a mathematical sentence that uses an equal sign, =, to show that two expressions are equivalent.
To write a word sentence in the equation form, look for keywords or phrases like “is,” “the same as,” or “equals” to find out where to put the equal sign.
Tom has $17 in his piggy bank. How much money does he need to buy a game that costs 68?
Let x be the amount of money Tom needs. Therefore, we can represent this problem with the following equation:
17 + x = 68
Subtract 17 from both sides of the equation to find the value of x
68 - 17 = x
Answer: x = 51; Tom needs $51 to buy the game.
Write the word sentence as an equation.
The sum of a number n and 7 is 15.
As “the sum of” means addition, rewrite “the sum of a number n and 7” as n + 7.
n + 7 = 15
Solve for x
15 - 7 = 8
Answer: n = 8