1. Gaston and Jordon are two budding chefs who unfortunately always misread the cooking time required for a recipe. For example, if the required cooking time is written as 1:32, meaning 1 hour and32 minutes, Jordon reads it as 132 minutes while Gaston reads it as1.32 hours. For one particular recipe, the difference between Jordon's and Gaston's misread times is exactly 90 minutes. What is the actual cooking time in minutes?
2. An integer has 3 digits in base 10. When it is interpreted in base 6 and multiplied by 4, the result is 2 more than 3 times the same number when it is interpreted in base 7. What is the largest integer, in base 10, that has this property?
3.Let x denote a single digit.The tens digit in the product of 2r7 and 39 is 9.Find r.
4.The circumcircle of a square ABCD has radius 10.A semicircle is drawn on AB outside the square.Find the area of the region inside the semicircle but outside the circumcircle.