If 5 times a number increased by 30 is 15, what is the number?

Mathematics

2 answers:

bija089 [108]3 years ago

7 0

Let's keep the,

Value of unknown number as y.

Then find the y,

→ 5y + 30 = 15

→ 5y = 15 - 30

→ 5y = -15

→ y = -15/5

→ [y = -3]

Therefore, -3 is the number.

weqwewe [10]3 years ago

3 0

Answer:

let x=the number

5x+30=15

5x=15-30

5x=-15

5x/5=-15/5

x=-3

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Can some one please help me will give 94 points for it

NNADVOKAT [17]

You can solve this by using "similar triangles".

In triangle ABC, we are looking for side AC which is x. Side AC is similar to side DF in triangle EDF.

You can solve for side x by picking two sides in triangle ABC and their corresponding sides in triangle EDF. This is what I mean:
$\frac{AC}{BC} = \frac{DF}{EF}$
Substitute for the values of AC, BC, DF and EF:
$\frac{x}{4} = \frac{11}{8} \\ \\ 8x = 4 \times 11 \\ \\ x = \frac{44}{8}$
$x = 5.5 \: units$
To solve for y, do the same thing. Pick two sides on triangle ABC and their corresponding sides in triangle DEF.
$\frac{AB}{BC} = \frac{DE}{EF}$
Substitute for the values and solve:
$\frac{3}{4} = \frac{y}{8}$
$4y = 24 \\ \\ y = 6 \: units$

We have the value x to be 5.5 units and y to be 6 units.