Question

2×(100+x)=400
700:y-2=5
200+(b+400)=1000
(800+x)-300=600

Answer 1

$200 + (b + 400) = 1000 \\ b + 400 = 1000 - 200 \\ b + 400 = 800 \\ b = 800 - 400 \\ b = 400 \\ Проверка: \\ 200 + (400 + 400) = 1000 \\ 200 + 800 = 1000 \\ 1000 = 1000 \\ = = = = = = = = = = = = = = = =$

$700 \div y - 2 = 5 \\ 700 \div y = 5 + 2 \\ 700 \div y = 7 \\ y = 700 \div 7 \\ y = 100 \\ Проверка: \\ 700 \div 100 - 2 = 5 \\ 5 = 5 \\ = = = = = = = = = = = = = = = \\$

$(800 + x) - 300 = 600 \\ 800 + x = 600 + 300 \\ 800 + x = 900 \\ x = 900 - 800 \\ x = 100 \\ Проверка: \\ (800 + 100) - 300 = 600 \\ 900 - 300 = 600 \\ 600 = 600 \\ = = = = = = = = = = = = = = =$

$2 \times (100 + x) = 400 \\ 100 + x = 400 \div 2 \\ 100 + x = 200 \\ x = 200 - 100 \\ x = 100 \\ Проверка: \\ 2 \times (100 + 100) = 400 \\ 2 \times 20 0 = 400 \\ = = = = = = = = = = = = = = =$

Answer 2

2*(100+х)=400
100+х=400:2
100+х=200
х=200-100
х=100

700:у-2=5
700:у=5+2
700:у=7
у=700:7
у=100

200+(b+400)=1000
b+400=1000-200
b+400=800
b=800-400
b=400

(800+x)-300=600
800+x=600+300
800+x=900
x=900-800
x=100