The experimental probability that Alexander wins a tennis match is 0.21 If he plays 38 tennis matches in the next month, how many whole number matches can Alexander expect to lose?

Start by representing the number.  Let the number be x.

Then "7 times a certain number" comes out to 7x.

When 25 is subtracted from that, the result is 7x - 25 = 101.

Add 25 to both sides:    7x= 126

Finally, solve for x by dividing both sides of the equation by 7.

x = 126/7 (reduce your answer).