book Maths Puzzle Numerical Ability

I am 50 years old and I am taking a online math course online and i cannot figure out this with the fractions in it:
Solve each inequality. Give the solution set in both interval and graph forms.

7/5(10z-1)<2/3(6z+5)

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book Other Question

5(X-7)squared = 135
My question is x = 7 + 3 square root of 3 or is the anwswer 10 square root of 3? Can I add 7 with 3 square root of 3?? HELP ME PLEASE!!!
Thank you.
Express the following in scientific notation

(a) (9.7 * 10^8)(8.5 * 10^3)


(b) (5.5 * 10^-7) / ( 9.1* 10^-2)