` a) ` ` 15.13 + 15.(-112) - 15 `
` = 15.(13 - 112 - 1) `
` = 15.(-100) `
` = -1500 `
` b) ` ` 2.(-3)^2 - 2020^1 : |-202| + 16 : (-2)^3 `
` = 2.9 - 2020 : 202 + 16 : (-8) `
` = 18 - 10 - 2 `
` = 6 `
` c) ` ` \frac{-23}{45} + \frac{38}{45} `
` = \frac{38 - 23}{45} `
` = \frac{15}{45} `
` = 1/3 `
` d) ` ` \frac{-1}{9} - 2/3 + \frac{5}{18} `
` = \frac{-2 - 12 + 5}{18} `
` = \frac{-9}{18} `
` = -1/2 `
