Chris made at least one error as she found the value of this expression. 2(-20) + 3[5/4(-20)] + 5[2/5(50)] + 4(50) Step 1: 2(-20) + 3(-25) + 5(20) + 4(50) Step 2: (3 + 2)(-20 + -25) + (5 + 4)(20 + 50) Step 3: 5(-45) + 9(70) Step 4: -225 + 630 Step 5: 405 Identify the step in which Chris made her first error. After identifying the step with the first error, write the corrected steps and find the final answer.
Simplify the following:
2 (-20)+3 (5/4 (-20))+5×2/5×50+4×50
5/4 (-20) = (5 (-20))/4:
2 (-20)+3×(5 (-20))/4+5×2/5×50+4×50
2/5×50 = (2×50)/5:
2 (-20)+3×(5 (-20))/4+5×(2×50)/5+4×50
3×(5 (-20))/4 = (5 (-20) 3)/4:
2 (-20)+(5 (-20) 3)/4+5×(2×50)/5+4×50
5×(2×50)/5 = (2×50×5)/5:
2 (-20)+(5 (-20) 3)/4+(2×50×5)/5+4×50
(-20)/4 = (4 (-5))/4 = -5:
2 (-20)+5×-5×3+(2×50×5)/5+4×50
(2×50×5)/5 = 5/5×2×50 = 2×50:
2 (-20)+5 (-5) 3+2×50+4×50
2 (-20) = -40:
-40+5 (-5) 3+2×50+4×50
5 (-5) = -25:
-40+-25×3+2×50+4×50
-25×3 = -75:
-40+-75+2×50+4×50
2×50 = 100:
-40-75+100+4×50
4×50 = 200:
-40-75+100+200
-40-75+100+200 = (100+200)-(40+75):
(100+200)-(40+75)
300-(40+75)
300-115
Answer: | 185
Your mistake is in step 2. You cannot combine two terms into one as you have it done, because:2(-20) + 3(-25) DO NOT equal: (3 + 2)(-20 + -25). Evaluate each term separately thus:( -40) + (-75)=-115. The way you have them combined comes to: 5 x (-45)=-225. A difference of -225 - (-115)=-110. The same applies to the last 2 terms. You must evaluate each term separately. That way you can't go wrong. The above answer of 185 appears to be right.
