Solve this literal equation 4a=2bc

Twice the sum of a number and 4 is equal to three times the difference of the number and 7. find the number.

Ten times the square of a non-zero number is eqaul to ninety times the number

The marked price of an article is 25% above its selling price and the cost price is 30% less than its marked price . find the discount percent and gain percent. only a brainlest can solve it i will mark you brainlest