Mark the numbers that are prime 12, 5, 17, 25, 31, 56, 43

A number that has only two factors, i.e. 1 and the number itself is known as Prime Number. For example, 3 is a prime number because it has only two factors 1 and 3 only. In the given set of numbers 5, 17, 31 and 43 are the prime numbers.

Add the following fractions: 2/3 + 3/5

Take the Least Common Multiple (LCM) of both the denominators (i.e. 3 and 5). LCM of 3 and 5 is equal to 15. Now divide the LCM by the denominator of the first fraction, i.e. 15/3 = 5. Now multiply the quotient with the numerator of the first fraction, i.e. 5*2 = 10. Now follow the same steps for the second fraction also. i.e. Divide the LCM by the denominator of the second fraction, i.e. 15/5 = 3. Now multiply the quotient with the numerator of the second fraction, i.e. 3*3 = 9. The answer will be (10 + 9)/LCM, i.e. 19/15

Solve the equation 5(-3x - 2) - (x - 3) = -3(4x + 5) + 13

We have the equation as 5(-3x - 2) - (x - 3) = -3(4x + 5) + 13 Now we multiply the factors in order to eliminate braces. After multiplying factors we get, -15x - 10 - x + 3 = -12x - 15 +13 On further simplification, We get -16x - 7 = -12x - 2 Now add 16x on both the sides. -7 = 4x - 2 After this, we have to add 2 on both the sides in order to separate out x term on either side of the equal to sign. -5 = 4x Now divide both the sides by 4. -5/4 = 4x/4 -5/4 = x Or we can write it as x = -5/4