Mark uses his calculator for 80% of his maths homework questions. Twelve questions are answered with his calculate
How many questions does Mark have for homework​

The number of questions in Mark's homework is:

Step-by-step explanation:

To identify the number of questions of the homework, first, you must identify the percentage that is the 12 question Mark calculates by himself: if in 80% he uses calculator, in 20% he doesn't, I mean, he uses his own calculates, by this reason:

With this data, we can use a simple rule of three and find the number of question that correspond to 80%.

If:

Then:

At last, we add the 80% and the 20% of the questions:

As you can see, the number of questions in Mark's homework is 60 questions.

a complex number is a number that can be expressed in the form a + bi, where a and b are real numbers, and i is a solution of the equation x2 = −1. because no real number satisfies this equation, i is called an imaginary number. has no real solution, since the square of a real number cannot be negative.