Question
A metal alloy is composed of 25% silver, 45% gold, and
30% copper. How much silver should be added to 50 kg of the alloy to make the new alloy contain 40% silver?Solution
ATQ,
Given: Alloy weight = 50 kg Composition: Silver = 25% of 50 kg = 12.5 kg Other metals (gold + copper) = 75% = 37.5 kg We add x kg of pure silver, so: New total weight = 50+x New silver amount = 12.5+x We want silver to be 40% of the new total: 
Solving the equation: 
What value should come in place of (?) in the given expression.
450 ÷ 9 + 75% of 160 − 64 ÷ 4 = ?
2/5 of 3/4 of 7/9 of 14400 = ?
7/3 of 4/5 of 15/56 of ? = 83
[564 + 32 of 18 × 9 ÷ 12 + 162 ] ÷ 4 = ?
What should come in place of (?) question mark in the given expression.
(25% of 320) + (3/8 of 400) − 30 = ?
45% of 360 - 160 + ? = √324
187 ÷ 5 ÷ 0.4 = ? – 24 × 2.4
Find the simplified value of the following expression:
[{12 + (13 × 4 ÷ 2 ÷ 2) × 5 – 8} + 13 of 8]
18 × 15 + 86 – 58 =? + 38
√(24²+285-8²-172) = ?²
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