How do you solve #0.7n+0.8n=2.1# ?

Question

2737 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-09-22T15:53:46

#n=21/15#

Multiply both sides by #color(blue)(10)#

#color(brown)(color(blue)(10)(0.7n+0.8n)=color(blue)(10)xx2.1)#

#7n+8n=21#

#15n=21#

#n=21/15#

Answer 2 · 2016-09-22T15:58:08

#n = 7/5 = 1.4#

#0.7n +0.8n = 2.1" "larr# Add like terms first"#

#1.5n = 2.1" "larr# isolate the variable #(div 1.5#)

#1.5/1.5 n = 2.1/1.5#

#n = 1.4#

While a calculator is obviously quick and easier, we can do this mentally as well.

#2.1/1.5 xx 10/10 =21/15" "larr# simplify by 3

#21/15 = 7/5 = 1 2/5#

#1 2/5 = 1 4/10 = 1.4#