<span>Being able to estimate your answer is a very useful skill. ... When decimals are involved, it's very easy to put the decimal point in the wrong place, and ... round all numbers to the same place value—this makes adding or subtracting a bit easier.</span>
First you have to find out the cost of the ticket. To do so you have to Divide 15 and 6. Which equals $2.50. So each ticket is $2.50 dollars. Now you have to multiple 2.50 times 9. which equals 22.5. So your total answer is $22.50 dollars
Let the x represent the unknown number.
"2 times a number" is 2x
"The sum of 2 times a number and 11" is 2x + 11
"The sum of 2 times a number and 11 is -7" is 2x + 11 = -7
Now we solve the equation for x to find the unknown number.
2x + 11 = -7
Subtract 11 from both sides.
2x = -18
Divide both sides by 2.
x = -9
Answer: The number is -9.
Check: 2 times -9 = -18
-18 + 11 = -7
The answer is correct.