Answer: The answer is 
Step-by-step explanation: Given that a school wants to put on a dance recital. The programs of Middle school dancer will be short of 4 minutes each and programmes of High school performers will be long of 7 minutes each.
Number of middle school dances is "M" and number od high school dances is "H".
Since there cannot be more than 10 dances all together, so fisrt inequality can be written as

Also, the entire recital must take maximum 90 minutes, so the second inequality can be written as

Thus, the pair of inequalities is

Answer: 20, 300, -50, 1,000, 80,000. Take the number 32; the choices to replace it with are 30 or 40 (they both have only one non-zero digit).
Step-by-step explanation: In front-end estimation, we replace the original number with a number that's close by but only has one non-zero digit.
It is 78 because you can draw a transversal with the line that 79 is on, and 79+23+x=180. so 180-79-23=78 therefore 78=x
understand?