Subtracting a number from another is the same as its additive . So, for all numbers a and b, a – b = a + (). ACTIVITY 1 Moscow, the capital city of Russia, is at 37.62 degrees longitude and 55.75 degrees latitude. Brasilia, the capital city of Brazil, is at -47.87 degrees longitude and -15.8 degrees latitude. Part A Write an expression to find the distance (in degrees) between the longitude lines of Moscow and Brasilia. |37.62 – ()| Part B Now, simplify the expression in part A, and explain what the number means with regard to the problem. |37.62 – ()| = |37.62 + | = || = The distance (in degrees) between the longitude lines of Moscow and Brasilia is degrees. ACTIVITY 2 Lenny is competing with his cousin, Jasper, in an indoor rock-climbing contest. At the start of the climb, Lenny makes his way 5 ¼ feet up the wall, while Jasper climbs 9 ¾ feet. How much farther did Jasper climb than Lenny? Part A Represent the problem with a subtraction expression: Name: Class: Program: SITC 2020 distance climbs − distance climbs 9 ¾ feet – 5 ¼ feet Start by (adding / subtracting) the additive inverse: 9 ¾ feet – 5 ¼ feet = 9 ¾ feet + ( ___ __/__ feet) Part B Then apply the commutative and associative properties to simplify the expression: 9 ¾ + ( __/__ ) = 9 + ¾ + ( ) + ( - __/__) = (9 − ) + (¾ - __/__ ) = __/__ feet Jasper climbed feet farther than Lenny. Summary When finding the difference in elevations, should you only consider the absolute value of the difference? Why or why not?