A students scores on the first three tests in a math course are 65,75 and 87. What range of scores on a fourth test will give the student an average that is less than 80 but no less than 70 for the four tests?

65+75+87+x/4 < 79.9, x<92.6

65+75+87+x/4 >(and equal to) 70, x>(and equal to) 53

So the range of scores would be 53 to 92.6? Is this correct and am I writing this down correctly?

Thank you very much