Can you solve the below algebraic mathematical equation?

(J+O+I+N+T)3 = JOINT

In a school, there are four subjects. Seventy percent of students study English, seventy five percent of students study Science, eighty five percent of students study Mathematics and eighty percent of students study Spanish.

Can you calculate the percentage of students that study all four subjects?

A thief enters a store and threatens the clerk, forcing her to open the safe. The clerk says, “The code for the safe is different every day, and if you hurt me you’ll never get the code.” But the thief manages to guess the code on his own. How did he do it?

How many points are there on the globe where, by walking one mile south, then one mile east and then one mile north, you would reach the place where you started?

John bought 150 chocolates but he misplaced some of them. His Father asked him how many chocolates were misplaced.
He gave the following answer to him:
If you count in pairs, one remains
If you count in threes, two remain
If you count in fours, three remain
If you count in fives, four remain
If you count in sixes, five remain
If you count in sevens, no chocolate remains.

Can you analyze the statements and tell us how many chocolates were lost?

Solve below popular number sequence
314 159 265 358 979 323 846 ?

Can you fill the blank with the correct number?

6 30 870 756030 _____

In a competitive exam, each correct answer could win you 10 points and each wrong answer could lose you 5 points. You sat in the exam and answered all the 20 questions, which were given in the exam.
When you checked the result, you scored 125 marks on the test.

Can you calculate how many answers given by you were wrong?

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?

What English word has three consecutive double letters?