Two triangles can be formed with the given information. use the law of sines to solve the triangles. b = 29°, b = 26, c = 28

According to law of sines, sinB/b=sinC/c. sin29 degrees=0.485, so we can solve for sinC in the equation, and sinC=0.522. Angle C=arcsin(0.522), there are two possibilities for C.
case 1:C=31.5 degrees approximately by a calculator. Angle A=180-29-31.5=119.5 degrees. We can solve for the length of a by using law of sines again. sinA/a=sinB/b, a=46.7
case 2: C=148.5. Angle A=180-29-148.5=2.5 degrees. SinA/a=sinB/b, a=2.34. 

For the substance to decay to one-half of its original amount, it will take:

10.6 weeks.

Step-by-step explanation:

The decay rate = dQ/dt= -rQ

Where r > 0.

100 mg of a mystery substance decays to 81.14 mg in 4 weeks

This implies that it has decayed by 18.86 mg (100 - 81.14) in 4 weeks

The rate of decay per week = 4.715 mg (18.86 mg/4)

For the substance to decay to one-half of its original amount, i.e. 50 mg (100 mg/2), it will take 10.6 (4/18.86 * 50) weeks.

We can also determine the time it will take the substance to decay by working with the decay rate and the volume of decay, thus:

Decay rate = 4.715 / week

Decay volume = 50 mg (100 mg/2)

Time for 50 mg to decay = Decay volume/Decay rate

= 50 mg/4.715

= 10.6 weeks