Answer:
a = 10
, d = 70
Step-by-step explanation:
Solve the following system:
{d = 7 a | (equation 1)
{d = 4 a + 30 | (equation 2)
Express the system in standard form:
{-(7 a) + d = 0 | (equation 1)
{-(4 a) + d = 30 | (equation 2)
Subtract 4/7 × (equation 1) from equation 2:
{-(7 a) + d = 0 | (equation 1)
{0 a+(3 d)/7 = 30 | (equation 2)
Multiply equation 2 by 7/3:
{-(7 a) + d = 0 | (equation 1)
{0 a+d = 70 | (equation 2)
Subtract equation 2 from equation 1:
{-(7 a)+0 d = -70 | (equation 1)
{0 a+d = 70 | (equation 2)
Divide equation 1 by -7:
{a+0 d = 10 | (equation 1)
{0 a+d = 70 | (equation 2)
Collect results:
Answer: {a = 10
, d = 70
