Answer:
D
Step-by-step explanation:
using the definition of n
= 
where n! = n(n- 1)(n - 2)......× 3 × 2 × 1
here n = 7 and r = 4, hence
7
= 
=
← cancel 3 × 2 × 1 leaving
7
= 7 × 6 × 5 × 4 = 840 → D
Answer:a
Step-by-step explanation:
That’s one cracked screen
X + 19 + 7x + 9 = 180
8x + 28 = 180
8x = 180 - 28
8x = 152
X = 152 : 8
X = 19
Answer:
A) 420 seconds = 7 minutes
B) 8 times
Step-by-step explanation:
A) After how many second would all three things happen together again?
Solution:
His clock ticked every 5 seconds , a tap was dripping every 7 seconds and his pet dog snored every 12 seconds. It all happens simultaneously = 5*7*12=420 seconds
B) How many times would all three things happen together again between midnight and one o'clock
Since all these events happen together after every 420 sec = 7 mins and there are 60 mins between midnight and 1 o'çlock , thus 60/7 = 8 times ....
4 x 5 - 3
= 20-3
=17<answer