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

Question

3416 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

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

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

How do you solve 0.7n+0.8n=2.10.7n+0.8n=2.1 ?