We know that he earns 420 every day. So if we want to know how much he earns over 5 days for example, we would multiply 5 and 420... 5 X 420= 2,100 We would do the same thing no matter how many days he works. * remember that in an algebraic expression having a variable and a constant next to each other indicates that they are being multiplied.
There is a very simple way of dealing with percentages. "increase" means add "decrease/discount/reduce" means subtract Now, we know that the original price is 100%. 100% = 1 (like 50% = 0.5) So if an object's price is x and it is 20% off, we get: 100%x - 20%x Taking x common, x(100% - 20%) = 0.8x Therefore, if we fist add/subtract the percentages we can multiply directly with the original to get the answer. This is as follows: 5] Increase 101 by 16% 1 + 0.16 = 1.16 So the answer is: 101 * 1.16 = 117.16 6] Decrease 36 by 21% 1 - 0.21 = 0.79 The answer is: 36 * 0.79 = 28.44 7] Let original price be x, we know it is 35% off 1 - 0.35 = 0.65 0.65x = 13 x = 20
