2.5 Exercises - Presentation of algebra 1. Write it as an algebraic expression for the number n. Ex A number n decrease by 4   n - 4 a) The sum of n and 12.   b) Double the number n.   c) 5 multiplied by n.   d) n divided by 7.   e) The difference between n and 10.   f) Three times the number n.   g) Six times the number n decreased by 9.           2. Write is as an algebraic expression. a) The sum of 12 and a number, n.   b) Eight less than seven times n.   c) The difference between the number n and 7.   d) n less than three times six.   e) Eight times the difference of n and 5.   f) Nineteen more than seven times n.   g) The sum of n and five times ten.           3. Jan has run x km.  Write a mathematical expression for: a) Rita has run 5 km less than Jan.   b) Nino has run 2 km more than Jan.   c) Per has run twice as far as Rita.           4. Ina’s age is x years.  Interpret the following algebraic expression in words. a) x - 2   b) x + 10